The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Embodiments relate to an apparatus to measure expansion of cement. The cement expansion measuring apparatus may be used in oilfield related applications, for example, to measure the expansion of cement exposed to downhole conditions of pressure and temperature. Another embodiment relates to a cement expansion measurement method.
Cement is used for zonal isolation of a well that has been drilled in a geological formation for the purpose of hydrocarbon exploration and production. Such cements are exposed to harsh environments encountered downhole, typically fluid mixtures of hydrocarbon and water at high pressure 2.8 kilobars (40,000 psi) or high temperature up to 315° C. (600° F.). Developing new cement formulations requires measuring the expansion of cement when exposed to such downhole conditions of pressure and temperature.
U.S. Pat. No. 6,817,238 describes an apparatus for placement in a high-pressure, high-temperature (HPHT) chamber, and a method of measuring volumetric changes in set cement as the cement is exposed to pressures and temperatures similar to downhole conditions. The apparatus comprises a mold having a first section adjacent a base and a second section movably attached to the first section and adjacent the base in which cement may be placed. The apparatus includes a sensor to measure the movement of the first and second sections relative to one another in response to volumetric changes in the cement.
Despite the valuable contribution of U.S. Pat. No. 6,817,238 to the art, it has been observed that the mold has a relatively complex structure, rendering the cleaning for re-use after a cement slurry has set in the mold and volumetric changes in the cement has been measured relatively difficult. Further, simulating the geometrical condition of cement expanding in an annulus of a drilled wellbore would require a different shape. Furthermore, estimating linear expansion of the cement and/or measuring commonly certified (e.g. International Organization of Standards ISO, or American Society for Testing and Material ASTM, or American Petroleum Institute API) characteristics of the cement would also be valuable.
All of the above described references are incorporated herein in their entirety by reference thereto.